Interactive process for use as a navigational aid and device for its implementation

ABSTRACT

The invention relates to a system to be used as an aid in navigation comprising a mobile terminal ( 1, 2 ) connected to a centralized server ( 5 ), and more specifically to the improvements required to convert a portable radiotelephone ( 1 ) into a complete and precise navigational aid system. The invention is characterized by the fact that the itinerary requests of the mobile terminal ( 1, 2 ) are transmitted to a centralized server ( 5 ) by a radio relay link, and by the fact that the server ( 5 ), which contains the necessary cartographic and program data, calculates the itinerary requested and transmits to the mobile terminal ( 1, 2 ) the data concerning the straight line and arc segments that constitute the itinerary, thereby permitting real-time guidance. The invention is further characterized by the fact that the server ( 5 ) evaluates the possibility of the craft deviating from its course, as well as by the fact that the server ( 5 ) also calculates and transmits the data concerning the segments of possible deviation itineraries in an area of proximity to the main itinerary. The invention can be applied in particular to automotive vehicles.

FIELD OF THE INVENTION

The invention relates to a navigational system connected to acentralized server and, more specifically, to the improvements requiredto convert a terminal (for instance a radiotelephone or an electronicorganizer) into a navigational aid system, particularly for automotivevehicles.

BACKGROUND OF THE INVENTION

Over the years, different types of navigational aid systems and of dataaccess have been developed particularly for automotive vehicles. Thesesystems make the driver's work easier by calculating the best itinerary(the shortest, fastest, simplest, or least expensive, etc.) to reach hisdestination and thereby spare him the trouble of reading a map whiledriving. These systems are particularly useful when driving inunfamiliar areas or for choosing the shortest course consideringreal-time road conditions (road works, traffic, demonstrations, weather,etc.).

Earlier state-of-the-art includes systems with integrated large screenswhich make it easier to read maps in vehicle integrated terminalsdedicated to automotive navigation.

These expensive devices have the capability to calculate the position ofthe vehicle so as to display it on a road map. The position of thevehicle can be determined with the aid of satellite signals receivers(the GPS, for example) or inertial or else by triangulation of thesignals emanating from ground stations (for example the base stations ofa mobile telephone system such as GSM).

Calculation of the position of a GPS receiver for example, is based onthe position data provided by three or more satellites and the delay oftransmittance of these signals to the receiver. However, the accuracy ofsuch systems is limited to about 100 meters, due partly to naturalcauses (weather variations, changes in the ionosphere, reflection onobstacles, etc.), and partly to deviations introduced deliberately onthe signals for the civil use of systems such as the GPS managed by theUS Defense Department. To make up for this lack of accuracy, earlierstate-of-the-art describes the use of differential GPS receivers,expensive devices that include an extra decoder, of the radio orsatellite type, to pick up signals providing corrective values, measuredby a fixed station that compares the real position of the station to theposition obtained from the satellite signals. In order to optimizereal-time calculation of the itineraries, these navigational systems aresometimes equipped with receivers picking up information on trafficconditions, for example the RDS system. These receivers further increasethe cost of the in-car terminal.

To make driving easier and safe for the driver, the systems aresometimes fitted out with voice recognition systems and/or with a voicesynthesis system which further complexify the navigational systems sincea microphone, a loudspeaker and at least one processor need to be addedto carry out voice recognition or synthesis or both. In all cases,real-time voice recognition and synthesis are carried out locally. Mostoften, the processing capability and limited memory of the in-carsystems allow for the recognition of isolated words only.

Finally, the cartographic data, which are essential for calculatingitineraries and for displaying the position of the vehicle, aregenerally stored locally, for example on CD-ROM, with the disadvantagesof a difficult updating and an increase in the cost, size andmanageability of the navigational system.

To offset such disadvantages, earlier state-of-the-art has systemsdescribing the partial use of a central cartographic data base linked byradio to the vehicle.

Some systems advocate complete transmittance of the cartographic data,which requires a very wide band or else imposes very long transmittanceperiods, given that data transfer on the GSM network is presently doneat 9,6 kbits/s.

Other systems propose transferring part of the data at the beginning,then on a regular basis according to the position of the terminal. Thislimits real-time usage of the data (calculating the length of thejourney, the distance to be covered, complete visual display of theitinerary).

Other partial systems propose transmitting only the itinerary and thelength of the journey, calculated by the central with eventual graphicelements for the display of intersections. Such systems are of littlevalue in real-time, and the guidance is inadequate, particularly becausediversions (blocked roads, missed exits, etc.), some of the moststressful events for a driver, are impossible to manage.

To allow for real in-car guidance, in particular with the aid of aportable telephone, systems using a central data cartographic base aretherefore lacking in the means by which the navigational system couldguide the driver even if he deviated from the route as first planned,for instance in the case of road works, blocked streets, trafficslowdowns or any other hitches or errors due to absent-mindedness. So,in the present state-of-the-art, either the complete data of the areasthrough which the driver journeys are transmitted to the terminal forlocal calculation, or the driver has to query the server again, with allthe ensuing delays, if only for the initial time required to establish anew connection.

Also missing in the systems using a centralized data base describedabove are the means by which the driver could visualize his position inconnection with general geographic landmarks without, in the process,overloading transmittance by sending details irrelevant to hisitinerary.

Also missing are the means which would provide the driver, in real-time,in text, graphic or voice form, with the directions to follow at everycrossroads; the means allowing the driver to give his order verballywithout a voice recognition system; the means allowing the navigationalsystem to calculate locally and in real-time the estimated length of thejourney and time of arrival; the means to obtain the exact position ofthe vehicle without using additional radio receivers or satellites forthe pick-up of the differential signals; the means to optimize theitinerary in real-time without using any additional radio receivers orsatellites for the pick-up of traffic data.

Finally, earlier state-of-the-art navigational systems are lacking inthe devices required for converting a portable telephone or anelectronic organizer into a real and complete navigational system.

SUMMARY OF THE INVENTION

The invention relates to a navigational system to be applied toautomotive vehicles for example, including a terminal equipped with themeans of communication giving it access to a centralized server throughradio relay, satellite or ground link, for example GSM, PCS, CDPD, SMS,PHS, CDMA, GMPCS. The server contains cartographic data and is capableof calculating itineraries. The server does not necessarily possessitself the means of communication but can be linked, for example throughInternet, to a gateway towards the radio relay network.

The mobile terminal includes the means to choose start and destinationpoints, to transmit a request including these points, and to ask thecentralized server to calculate the best itinerary according to criteriaselected by the user (the fastest, simplest, least expensive, shortest,with or without highways, the most pleasant, going through such or suchintermediary points, by foot, on a bicycle, by metro, in a bus, etc).

The terminal also includes the means to determine automatically theposition of the vehicle, either by using a satellite locating system ofthe GPS type or an equivalent, or by using the base stationtriangulation system of a cellular telephony network, or through anyother method.

The start position which is part of the itinerary request is preferablythat of the vehicle as determined in an automatic manner; entering thestart address by hand is thus bypassed.

The invention is characterized by the fact that the centralized servertransmits the itinerary in vector form, that is, straight line and arcsegments, including, for each segment, at least the latitude andlongitude coordinates of its extremities (or of at least one, since theother one can be determined by checking where begins the next segment),thereby allowing a local graphic yield and the positioning of theterminal on the itinerary and eventually the type of road (street,boulevard, national, highway, etc), which in turn makes the transmissionof messages easier. The server also transmits typical information forthat type of road, the average speed expected on the road, if differentfrom the normalized speed for that type of road, thereby allowing themobile terminal to estimate in real-time the length of the rest of thejourney, and the name of the road, thus making it possible to transmitsuitable messages. Other information may also be transmitted, such aswhich way the street runs, the height allowable on the streets, etc.

The invention is further characterized by the fact that the navigationalsystem includes in the vehicle itself the means by which to pick up thisinformation and to store it, the means to obtain on a regular basis theposition of the vehicle, to display the position of the vehicle on amap, on the base of the received segments, to calculate in real-time theestimated time of arrival, to transmit guidance or information messagesrelevant to the position, in text, graphic or sound form. Thus, a fewseconds before a change of direction (according to a programmabledelay), the mobile terminal can transmit messages such as: “take thesecond to the right, Montrouge street”, “in 2 km, take exit 106, towardsEastman”, etc.

The invention is also characterized by the fact that in addition to theitinerary, the server transmits to the terminal the route segmentscrossing the itinerary, as well as, if possible, the type of priority ofeach of the crossroads (stop, lights, priority to the right, etc.) plus,if possible and when required, data allowing identification of thedestination to which the intersection leads (for instance, the name ofthe main towns/cities to which the road leads).

The invention is also characterized by the fact that the centralizedservice estimates the possibility of the vehicle deviating from itscourse and taking one or the other of the crossroads. For one, severalor each of the possible deviations, the centralized service calculatesand also transmits to the terminal the best alternative itinerary forthe driver to follow in order to reach his destination, thusestablishing an area of proximity information around the itinerary.According to a programmable parameter, the process can be repeated so asto provide a third, fourth, etc level of itinerary in case the vehicledeviates from one of the recommendations of the preceding level.

The invention is further characterized by the fact that the navigationalsystem includes, inside the vehicle, the means required to verify theposition of the vehicle compared to the planned itinerary, to determineif the vehicle has taken one of the intersections instead of therecommended course and, in that case, to advise the driver that theprecalculated secondary route is now used, if one is available, and togive instructions based on this secondary route.

If a secondary itinerary is not available, or if the vehicle deviatesfrom the new recommended itinerary, or for each level of pre-storeditinerary, one of the third (or umpteenth) levels of transmitteditineraries, then the mobile terminal, after informing the driver,contacts the centralized server automatically and transmits theposition, asking the server for a new itinerary to reach the originaldestination.

There are multiple advantages to the transfer of information on whichcrossroads and itineraries to follow in case of deviations or drivingerrors. Among other things, no program of local calculation of itineraryis required, thereby simplifying the in-car guidance program; also, thedegree of capability required for processing and memory is lower, plusit reduces the cost of the mobile terminal. This allows an enrichedvisual display by indicating crossroads and nearby roads, it makes itpossible to recommend immediately and without delay a new itinerary inthe case of deviations, to display at all times a graphic representationof alternative routes according to the position of the terminal, therebymaking it possible to estimate autonomously and rapidly the impact ofdetouring, for instance to drive by an incident (slowdown, accident,blocked road, etc).

The invention is also characterized by the fact that the server can savethe information (itinerary, proximity area, etc) transmitted to themobile terminal, that it can obtain information regularly on roadconditions (traffic, demonstrations, road works) and/or weatherconditions, that it can verify regularly if the information affects theitinerary or its proximity area and, if it does, to transmit thisinformation to the mobile terminal and, if useful, for instance when atraffic jam can be bypassed, it can also transmit a new itinerary to themobile terminal, which then informs the driver of the change and guideshim through the deviation.

The advantage is that no additional receiver for the pick-up of trafficinformation is required in the vehicle, thereby reducing the cost of thein-car system. If the mobile terminal transmits its position to theserver at regular intervals, the server will take this into account toverify if a traffic or weather incident is really relevant beforeadvising the mobile terminal. The server can also consult the mobileterminal on its position so as to verify if the changes are importantbefore transmitting this new information.

The mobile terminal can also be equipped with traffic data receiversand, on its own, make the necessary adjustments to allow a newestimation of the length of the journey and also verify if any of thedeviations of its proximity area are more advantageous. It can also askthe server if there is a new and more advantageous itinerary given thesenew real-time weather conditions.

The invention is further characterized by the fact that the server canhave in stock or be linked to other servers which have in stock, displaydata, for instance stills or video images of crossroads, or informationallowing the tridimensional projection of the view a driver followingthe indicated itinerary would have of a crossroads, by the fact that theserver transmits the information to the terminal, where they are stored,and by the fact that the mobile terminal can present the displays at theappropriate time according to its position. This is particularly usefulin case of doubt, or of errors in estimating the position and, inparticular, at crossroads or traffic circles where, 3, 4 or 5 roadscross each other.

The invention is further characterized by the fact that the server canhave a database or be connected to other servers with a database holdinggeneral information relevant to the itinerary, such as gas stations,restaurants, hotels, tourist, historical or geographic information. Theserver can transmit this information to the mobile terminal when theitinerary is requested or on request during the journey.

The invention is further characterized by the fact that the driver'sreal-time information or guidance messages can be done in audio form.The advantage is that it makes the driver's work easier, thus makingnavigation safer because the driver is not required to keep a constanteye on the terminal screen. It also allows the use of a terminal withlimited display capacities, for example a GSM phone with a 4 line screenor even an accessory without any display function, for example atelephone accessory such as a hands-free kit for mobile telephones, theprocessing being done not in the telephone itself but in the accessoryto which the telephone is grafted, the telephone then being used solelyas a communication module.

These sound messages can be generated by the server according to theitinerary or the position of the terminal, be transmitted to the mobileterminal, either at the time of the initial request or during thejourney, be stored by the latter and, as is or in a combination, beplayed back at the appropriate time by the mobile terminal according toits position. The advantage is that it reduces the complexity and costof the mobile terminal and also that the choice of language and theergonomics of the dialogue are not frozen within the mobile terminal.

These messages can also originate locally from a speech synthesissystem, at the appropriate time according to its position. This has theadvantage of reducing the amount of information the server transmits,but a voice synthesis system is required.

The invention is further characterized by the fact that the requests canbe done in voice form. The advantage is that it allows a safer interfacebecause it is less dangerous for the drivers who need to focus theirattention on driving and keep their eyes on the road. This also makes itpossible to control or consult the navigational system without having tostop the vehicle. Thus, while driving, information such as the remainingdistance or time, the distance to the nearest gas stations, hotels orrestaurants, or a description of the surrounding tourist area (such as“what is that castle on the right?”) etc, can be obtained.

So, the mobile terminal digitizes voice and extracts parameters from itfor analysis, after which the mobile terminal transmits the parametersto the server, in general along with its position. The server thenproceeds with the recognition, searching with the aid of a word list orphonemes bank, determines the object of the consultation and thentransmits its answer to the mobile terminal.

Local digitization and extraction of the analysis of parameters providea sampling covering an important part of the frequencies of the humanvoice (a sampling at the Nyquist frequency of 44 kHz for example). Byanalyzing and extracting the parameters before transmittance to theserver, one avoids speech distortions caused by the reduced bandwidth ofthe telephone channels (generally limited to 4 kHz) and by the speechcompressions effective in digital telephony (the Full Rate or EnhancedFull Rate coding, for example), distortions which make centralized voicerecognition difficult to execute.

So, speaker-independent recognition of natural language becomes possible(rather than the recognition of isolated words from aspeaker-dependent), the size of the vocabulary can also be larger andthe centralized recognition system can possess a level of memory and acalculation capability that would be too prohibitive for installation ina vehicle. This is particularly important for automotive navigationwhere the number of cities, streets, etc is generally higher than thesize of the vocabularies that can be processed locally. Multilingual andspeaker-independent recognition then becomes feasible.

The advantage of transmitting all at once the analysis of the parametersand the position of the mobile terminal is that it totally frees thenavigational system user (the driver) and makes his or her task easier.The risks of errors in the voice recognition system are also lower sinceonly one request can be made at a time, thereby reducing the risks ofstress and danger for the user at the wheel and allowing the supply ofinformation related to the immediate position.

Of course, voice recognition can also be done locally, with theadvantage that it limits the amount of information exchanged between theserver and the mobile terminal, but a more complex mobile terminal isrequired and limits are imposed on the performance of the voicerecognition system.

The mobile terminal can use a satellites positioning system, of the GPStype, for example.

The accuracy of the position measured locally by the mobile terminalwith the aid of signals picked-up simultaneously from the satellites ofa positioning system by satellites of the GPS type can be improved byusing differential information, obtained from one or several fixedstations, whose position is known, picking-up simultaneously the signalsof the same satellites. Generally, differential information comprise thedistance measured (called pseudo-range) between the receiver of thefixed station and each of the satellites, and the real distancecalculated from the known position of the fixed station. The increasedprecision is due to the fact that over a distance of about 500 km, theerrors of a positioning system of the GPS type are very similar.

The invention is characterized by the fact that differential informationis transmitted by using the same radio relay network used for itineraryrequests and answers. That way, there is no need to use another receiver(satellites, RDSIFM, etc) to pick-up differential information, therebyreducing the complexity and cost of the mobile terminal.

The network is preferably of the GSM type, or of the GMPCS (GlobalMobile Personal Communications by Satellite) and, preferably, supportsthe transmittance of short messages of the SMS type.

The invention is also characterized by the fact that differentialinformation can be transmitted by SMS from the server to the mobileterminal, at regular intervals, for instance every 10 or 30 s. Theadvantage of using short messages of the SMS type is that they can betransmitted even when the radio link is being used during atelecommunication, which makes it easier to use the same network for thetransmittance of differential requests, answers, corrections and avoidsthe use of a device dedicated to the sole reception of differentialinformation.

The invention is further characterized by the fact that the server canbe an Internet server which makes its use possible on a world-widebasis, since access to Internet is available throughout the world. Themode of connection being standardized, the use of several types ofterminal is also possible. Furthermore, one can take advantage of thefact that several services which can be useful for people on the go areor will be available on Internet, of the fact that the server will beable to access them after an agreement with the supplier of thisinformation, and that it will be possible to select the data whileconsidering the position of the terminal. That way, all the data are notnecessarily managed nor stored by the server.

The invention is further characterized by the fact that the vehicle cantransfer its position to the server on a regular basis, that thesepositions can be stored by the server, and that the server can provideone or several third party terminals, including mobile ones, and inparticular through Internet, with information on the position of themobile terminal, at all times. This is particularly useful for locatingthe vehicle and for fleet management, making it possible to offer bothnavigational aid and fleet management services, to offer the services bysharing cartographic data with several companies which then do not needto each have their own complete system of fleet follow-up andmanagement. Other information can be exchanged, such as messages, thecondition of the vehicle, the length of the journey, speed, weather, thenumber of turns per minute, the distance already traveled, etc.

Preferably, the information supplied by the server to the third partyterminal contains cartographic data in vectorial form corresponding toat least one position of the mobile terminal and includes a program forthe display of this information by the third party terminal (a Javaprogram, for example).

The invention is further characterized by the fact that the server canreceive requests for calculating itineraries from another terminal(mobile or not) and transfer the itineraries requested to the mobileterminal (and eventual further messages). This allows severalalternative ways of implementing the service. For instance, a person canmake a connection through Internet or Minitel from his or her house orany other place, request an itinerary, provide the number of his or herportable telephone; the server will then transfer the appropriateitinerary and data to the telephone. Requests can also be made bytelephone to an operator who consults the server and transfers theitinerary to a mobile terminal, for example a terminal installed in avehicle. Among other things, this makes it possible to use as a mobileterminal a portable telephone with a limited keyboard, on which enteringan address would be rather fastidious. It also makes it possible to makevoice requests about itineraries while at the wheel of a car and allowsusage even while driving, which is safer and does not require a voicerecognition system.

The invention is further characterized by the fact that the programs ofthe mobile terminal (extraction of parameters for analysis, real-timeguidance, graphic display, etc.) can be telecharged from the server tobe stored and executed locally. This offers the advantage of a quickupdate of the programs when new functionalities become available or tocorrect errors. Another advantage is that it makes it possible forseveral types of terminals to act as navigational aid systems. It alsoallows the use of terminals with more limited storage capacities, theprograms being transferred only when required.

The invention is characterized by the fact that a mobile telephone or anelectronic organizer can function as mobile terminal for thenavigational aid system. Using a telephone or an electronic organizerhas the advantage of limiting the number of devices in a vehicle andalso of using a device that can be carried everywhere and employed forother functions, rather than a single device dedicated to automotivenavigation. Its modulability makes it possible to separate it from othercomponents, for instance, analog-to-digital converter, voicerecognition, synthesis, loudspeaker, remote microphone, etc. Forinstance, the map display function could prove very useful forpedestrians, with or without integrating the sensor of a positioningsystem of the GPS type. The other interesting aspect of using atelephone or an electronic organizer detachable from the othercomponents, including eventually the receiver of the GPS type, is thatit is then possible for the driver to consult the server and to plan histrip from outside his vehicle, and eventually to inquire about roadconditions before actually sitting behind the wheel. Once connected to apositioning receiver by satellite in the vehicle, the telephone andelectronic organizer can guide the driver during the complete itinerary.Moreover, using a portable telephone is an advantage because the ownerof the telephone will be likely to buy a hands-free kit with anintegrated receiver of the GPS type. Another advantage of using aportable telephone is that it comes with an integrated screen andkeyboard (or touch screen or light pen) and that it possesses thecommunications components required for implementing this navigationalsystem. Thus, no other screen is required, nor any other communicationsmodule (not for request, nor for answers, nor for differentialinformation). This also allows the use of a radiotelephone network, forinstance short messages of the SMS type, accessible almost everywhere(and soon, with the satellites networks, everywhere), and then nothaving to depend on transmitting sources of the RDS type using a FMband.

In cases where the mobile terminal comprises a portable telephone, it ispossible either to calculate the analysis parameters directly inside thetelephone, or from outside the telephone and, in this latter case, touse the telephone as a communications module. The advantages ofcalculating the parameters in the hands-free kit are that, often, italready includes a microphone and a processing unit. That way also, atelephone that has not been modified at all can be used.

So it is possible to have a 100% voice solution by using a telephonethat has not been modified at all, all the guidance and requests beingmade by voice.

The totality of the programs required for the navigational aid systemdescribed above can also be integrated and executed either on thetelephone or the organizer, either in the hands-free kit or any otheraccessory connected to the telephone.

Other characteristics and advantages of the invention will becomeapparent from the following description, done for illustrative purposesonly and not in the least limiting, referring to the figures herebyappended on which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 represents the global view of a navigational system for aportable telephone with access to a centralized server and thetransmittance of differential information of the GPS correction, witheventual transfers by a call center.

FIG. 2 represents the in-car components which allow accessing acentralized data base, measuring the position and interacting with thedriver.

FIG. 3 represents the communications process between the terminal andthe centralized server during a query on itineraries.

FIG. 4 represents the process which allows local use of this informationfor real-time guidance of the vehicle driver.

DETAILED DESCRIPTION OF THE INVENTION

According to a preferred mode of implementation, referring to FIG. 1,the mobile terminal comprises a portable radiotelephone 1 connected to ahands-free kit 2, preferably fixed inside a vehicle, the ensemble 1 and2 forming the mobile terminal. This is presented as an example, sincethe elements of the kit 2 can be integrated to the telephone, or thewhole ensemble integrated to a computer aboard the vehicle. The mobileterminal 1,2 is joined by radio link to the centralized server 5. Theserver 5 transmits the itinerary data to the mobile terminal 1,2 andalso the differential corrective data obtained by a fixed station 6including a receiver 7 for positioning by satellites. Communicationbetween the server 5 and the fixed station 6 is done, for example by theInternet network 4.

Referring to FIG. 2, the kit 2 includes a microcontroller 16, fromrandom access memory 17 of the Random Access Memory (RAM) type forexecuting its programs stored on a permanent memory 12 of the ErasableProgrammable Read Only Memory (FLASH-EPROM) which can be reprogrammed.

Preferably, power feed 13 of the microcontroller and other components issupplied by the vehicle, by plugging it to the lighter for instance. Thehands-free kit includes a group of connectors 11 compatible with theconnectors 10 of the portable telephone 1, allowing the exchange of dataand an eventual electrical feed of one by the other.

The user of the mobile terminal 1,2, for instance the driver of thevehicle, can obtain an itinerary by transmitting his request to theserver 5, FIG. 1, via a radio relay link, relayed, for instance, by abase station 3 from a cellular telephone network or by satellitenetwork, for instance a low or average orbits satellites network of theIridium or Globalstar type. The server includes the cartographic databases and the programs for calculating the itinerary. The server is aserver linked to the Internet network 4, the exchange of data being donethrough TCP/IP (a non-limiting example).

The request includes a choice of destinations, an address for instance,or the name of a person or company, the server being able to accessdirectories of the white or yellow pages type, allowing a link to beestablished between a name and an address. The request can also be moregeneral, by asking, for instance, for the nearest gas station, automaticbanking machine, restaurant so and so, drug store, the server then makesthe required search, using this information to determine the requireddestination. The request includes a start position which can bedetermined automatically by the terminal or entered by the user himself.The request also includes the optimization method of the itinerary asspecified by the user.

Referring to FIG. 3, the request is entered on the terminal, step 25.The request is entered according to the preferred implementation mode asexpressed in a voice request described further on, but this request canalso be entered with the aid of a keyboard, light pen or touch screen,etc. The position is determined automatically, step 26, the mobileterminal 1,2 transmits the request to the server 5 by radio relay, step27, in the present case by using the data transfer protocol of a GSMnetwork, although any other method of wireless communicating can beused.

The server 5, with an access to cartographic data (not illustrated),calculates the best itinerary and identifies the courses to be followedby straight line and arc segments, step 28. Data are extracted for eachsegment, in particular the position of its extremities (latitude,longitude, altitude, for instance) or of at least one of theextremities, the end of a segment, for instance, since the other one canbe determined by checking where begins the next segment. The data alsoinclude a description of the type of road (national, highway, street,boulevard, etc.), the name, the length of the itinerary (in kilometersor miles), the average speed expected on the segment (eventually infunction of the time of day and taking into account the traffic datastatistics) or by directly considering real-time traffic and weatherdata, obtained by automatic means or entered by operators. The advantageof also using weather data is that in the case of rain, snow or fog, theaverage speed will preferably be reduced.

It will be possible not to transfer the average speed for each segmentbut for each type of segment (for instance, average speed on streets=45km/h, average speed on highways=120 km/h), transferring a differentspeed for each segment only when necessary.

Eventually, the server 5 will be able to return intermediary resultsimmediately to the mobile terminal 1,2, for instance the estimatedlength of the journey and the proposed main roads, and also to proposeseveral options, asking for confirmation from the mobile terminal 2,before continuing with the next steps.

The server 5 also estimates the roads (streets, highways, etc.) crossingthe itinerary and, taking into account information on the way thestreets run for instance, it estimates the possibility for the vehicleto take these roads, step 29. Data similar to the data of segments ofthe itinerary are also identified. They will allow the display on themobile terminal 1,2 of a proximity area around the itinerary. The servercan also identify the main roads around the itinerary and the generaltopography (outline of a city, borders of a country, rivers) which willmake it easier to display information on itineraries.

The server will be able to choose to retain all the roads crossing theitinerary, or only the most probable, according to criteria such asaverage speed of the road, traffic density, visibility, the degree offamiliarity of the driver with the itinerary or else only a few, atregular intervals. Preferably, the server will choose to keep at leastthose segments corresponding to continuations, that is, situations wherethe user does not take an exit on a highway or does not followrecommendations for turning to the left or to the right on a givenstreet. Very often, these are stressful situations where the user, awarethat he did not follow, or that he followed only part of therecommendations, feels anxious and will be reassured if the navigationalsystem can provide him without delay with an alternative solution.

The server 5 estimates for each selected route an itinerary (the best orthe simplest one) which will lead the vehicle to its destination even ifthis deviation is taken (by mistake or constraint) step 30. Eachitinerary will include the same type of information as the main one(position of the extremities of the segments, type of road, averagespeed, etc.).

Preferably, the server 5 will not transmit data on segments that havealready been transmitted.

According to this preferred implementation mode, the server 5 keeps theselected itinerary and preferably the annexed data, step 31, so thatthey can be used later on. Preferably, the server does not keep all thedata but keeps, instead, indexes referring to the basic components ofthe cartographic data.

The server 5 then transmits the information calculated on the itineraryand the proximity area to the mobile terminal 1,2, step 32. The mobileterminal 1,2 receives and stores its information, step 33, so as to useit as real-time data sources. Contact between the server and the mobileterminal 1,2 is now cut, which reduces the cost of the communication,for billing is generally based on time units.

If the data to be transmitted are too important, the server 5 couldeventually transmit the totality of the itinerary data and only theproximity data corresponding to the first part of the itinerary. Themobile terminal 1,2 could then, from time to time, ask the server totransmit the rest of the proximity data. It is important that the wholeitinerary be transferred even if all the proximity data are nottransmitted, so that the mobile terminal 1,2 can recalculate inreal-time the estimated length of the journey and the remainingdistance, and provide the user with a graphic representation showinghim, in a relative manner, his position as compared to the remainingportion of the itinerary.

Referring to FIG. 4, the mobile terminal 1,2 can now use thisinformation in real-time. It obtains its position regularly, step 34(every second, for instance), then verifies if the position appears onthe itinerary, step 39. Since errors in reading the position orinaccuracies in the cartographic data are a possibility, the mobileterminal 1,2 will consider the previous position, the nearest segment ofthe measured position, and physical limits, to determine its position ina more accurate and more probable way.

If the mobile terminal 1,2 notices that it has come out of itsitinerary, it then checks for the presence in its proximity area of anitinerary allowing the vehicle to reach its destination, step 35. Ifthere is one, it obtains the new itinerary directly, step 37, and ifthat is not the case, it then queries the server 5, for a new itineraryand provides its current position, step 36. In both cases, it is now thenew itinerary that will be used for guiding the vehicle, step 38.Preferably, the mobile terminal 1,2 shows a message indicating itsawareness of the deviation and that the appropriate measures will betaken.

Never, at any time, is the mobile terminal 1,2 required to recalculatean itinerary, therefore there is no need for it to keep a search programlocally, which could prove complex, especially if multiple optimizationcriteria (the shortest, fastest, with or without highways, the leastexpensive, going through such or such an intermediary point, etc) are tobe considered.

The mobile terminal 1,2 then proceeds to update a graphic displayindicating its position on the map, comprised of the segments of theitinerary (with or without the data from the proximity area), and mayalso make certain calculations such as the length of the journey and thedistance still remaining before arrival, step 40.

The mobile terminal 1,2 then estimates the distance and the length ofthe journey before the next change of direction, and verifies, accordingto criteria modifiable by the user, if it is close to it, step 41. If itis, the mobile terminal 1,2 can display the relevant information ortransmit a guidance message, step 42, for instance, “take the next exitin 2 km”.

The server 5 receives information on road conditions and/or weatherconditions on a regular basis. Preferably, the server 5 will have savedthe previous conditions in memory and will be able to verify if anychanges have occurred, then update the data concerning the speeds on themain roads already in its cartographic data base. The server 5 canfollow several mobile terminals and, for every one, verify if the newroad conditions apply to its itinerary.

If they do, the server 5 determines, if possible, the position of themobile terminal 1,2. It will be possible to estimate this positioneither from the positions transmitted on a regular basis by the mobileterminal 1,2, if it does such an operation, either by asking itsposition to the mobile terminal 1,2 either by estimating its positionconsidering its last known one (eventually, the start point of theitinerary) and the time elapsed since this last measure.

The server 5 then estimates if the planned itinerary is affected by thenew data on road conditions (changes in average speeds, blocked roads,accidents, etc.) or if they are relevant for the driver. If they are,the server 5 transmits this information to the mobile terminal 1,2. Themobile terminal 1,2 will then be capable of transmitting messagesinforming the driver of the situation, and use for instance new data onthe average speed of the roads to recalculate the time of arrival.

The server 5 then estimates the best itinerary considering the new dataand verifies if the itinerary is different from that on the mobileterminal 1,2. If it is, the new itinerary is transmitted to the mobileterminal 1,2 which can then notify the user and either follow the newitinerary automatically, or suggest the proposed deviation to the user.

The server then repeats the procedure for each mobile terminal 1,2 downto the last one.

Data on road conditions can be transmitted to the server 5 either bywire link, or by radio relay link. Using relay stations which wouldpick-up information transmitted by RDS transmitters and transfer them tothe server 5 is also a possibility.

Referring again to FIG. 2, the hands-free kit comprises or is connectedto an analog-to-digital converter 21 and to a loudspeaker 23, whichallows it to transmit sound messages. These messages can be generatedeither by a voice synthesis program executed either on themicrocontroller 16 or on a special processing unit 24, a Digital SignalProcessor (DSP), for example.

Sound messages can also have been originated by the server 5 andtransmitted to the mobile terminal 1,2 directly in digital format, thenstored, for example in memory RAM 17 or in flash memory 12. Soundmessages can be either comprised of prerecordings, either generated by avoice synthesis system integrated or linked to the server 5.

Preferably, sound messages have been compressed so that theirtransmission time is not too long. Preferably also, sound messages areidentified by a code through which their meaning and language can beobtained. Before transmitting a message, the server 5 first transmitsthe number of the version of the message; before accepting thetransmission, the mobile terminal 1,2 verifies if the message is notstored in memory already.

The hands-free kit also contains a microphone 22, an analog-to-digitalconverter 20 and a processing unit 24, a DSP for example, which makes itpossible to digitize voice commands transmitted by the user.

The user turns on the voice recognition activity for instance bypressing a key. The mobile terminal 1,2 can also be on permanentlistening mode and detect a level of sound activity corresponding tothat of a person who starts talking.

The sound signal is digitized at regular intervals, for instance every16 ms, and saved in a buffer for later processing. Processing unit 24then calculates analysis parameters, through a digital filter followedby a Fourier transform, followed by an anti-noise filter in frequencyand by a calculation of cepstrals.

Once the position is known, the mobile terminal 1,2 transmits theseparameters to the server 5. Transmission can be done either in a block,for instance once the end of the voice activity has been detected,either piece by piece throughout the listening period. The server 5 thenexecutes the search from the words or phonemes models it has in memory.

The server 5 can first transfer the results of its recognition and askfor confirmation from the mobile terminal 1,2 before continuing. Forinstance, the mobile terminal 1,2 will display the recognizeddestination address and ask for a confirmation which will be transmittedto the server 5.

The server 5 then establishes the nature of the request, for instance acalculation of itinerary with a destination, or the transmission of amore detailed map of the area.

The server 5 then transmits the data (for instance an itinerary or amore detailed map of the current position of the mobile terminal 1,2)corresponding to the results as well as the results themselves (theaddress of destination for instance). The mobile terminal 1,2 thendisplays the results, stores the data and processes them if necessary.

Processing and digitization can also be done directly inside thetelephone which already contains the converters and processing unitsrequired for this type of operation.

Voice recognition can also be done totally locally, for instance on aprocessing unit 24 or a microprocessor 16, with words models or phonemicor allophonic models stored in flash 12 or transferred by the server 5.

Different means can be used to obtain the position previously described,in particular through triangulation of the base stations of a mobiletelephony network, or through a satellites positioning system, forexample of the GOS or Glonass type. The preferred implementation modeuses a receiver from the Global Positioning System (GPS).

Returning to FIG. 2, microcontroller 16 receives information on aregular basis, which makes it possible to establish its position withthe aid of a GPS receiver 19 picking-up through its antenna 18 signalscoming from satellites 8 a, 8 b, 8 c, FIG. 1. The microcontroller canalso use information from other sources to determine the position of thevehicle, for instance from sensors measuring the distance alreadytraveled 14 or the direction 15. The cruising speed of the vehicle, asmeasured by the GPS receiver through Doppler effect, can also be usedfor a more refined estimation of the position.

The position can also be improved by using differential data. The fixedstation 6, FIG. 1, with a known real position, picks up GPS signalsregularly from the same 8 a, 8 b, 8 c satellites with the aid of areceiver 7 and, that way, measures its position like a mobile terminal1,2 would measure it. The fixed station 6 calculates the differentialdata and transmits them to the server 5.

The method for calculating GPS differential data is already known (seein particular “GPS Theory and Practice” by Hofmann-Wellendhof,Lichtenegger and Collins, Springer, 4th edition). It is possible tocalculate either the difference between the known position and theestimated position, or the difference between the real distances at agiven time and the estimated distances between the fixed station 6 andthe satellites (pseudo-ranges).

Transmission to the server 5 can be done either by wire network 4,Internet for instance, or by radio link network. So as to benefit fromthe fixed stations already in place in a given area, it is also possibleto use relay stations picking up differential information transmittedthrough RDS by the fixed stations and to retransmit them to the server5.

The server 5 receives the differential data, preferably from severalfixed stations. Preferably, the fixed stations are distributed so as tocover an important part of the area to be served. Accuracy being morenecessary in cities, stations will be installed there as a priority.

The position of each mobile terminal 1,2 is determined by the server 5.Accuracy is not important here, it is simply a question of determiningin which geographic area the mobile terminal 1,2 is located. Simplyknowing the itinerary could be sufficient. The server 5 then determineswhich fixed station is nearest to the mobile terminal 1,2 and figures ifit is sufficiently close to the mobile terminal 1,2 to justify sendingcorrective differential data. If it is, the data are transmitted to themobile terminal 1,2 with the exact time at which they were measured.Preferably, the data are transferred at regular intervals, for instanceevery 10 or 30 seconds.

Preferably, differential data will be coded according to the standardRTCM-SC-104 (Radio Technical Commission for Maritime Services, SpecialCommittee 104), and transmitted from the server 5 to the mobile terminal1,2 by using the same transmission network used for the previousexchanges between the mobile terminal 1,2 and the server 5.

Here, transmission is done by using short SMS messages on the same GSMnetwork, the messages being received directly by the microcontroller 16which has exchanged with the telephone the required commands for it tointercept SMS messages transmitted to the portable telephone, accordingto the protocol described by norm GSM 07-05 of the EuropeanTelecommunication Standards Institute (ETSI), by a serial link using aconnection 11 and linked to a connector 10 of the portable telephone.The transfer frequency of the differential data transmitted by theserver 5 to the mobile terminal 1,2 can be reduced by transmitting notonly the pseudo-ranges corrections (PRC), but also the correctionscalled range rate corrections (RRC). By using the latter, the errorsaccumulated on the mobile receiver are of the order of 1,5 meters after30 seconds.

The microcontroller 16 reconverts the SMS data into a RTCM-SC-104 formbefore transmitting them to the GPS receiver 19 by using a dedicatedserial link. Most GPS receivers available on the market integrate thisfunctionality. The GPS receiver 19 of the mobile terminal 1,2 transmitsits position regularly, for instance every second, with an eventualcorrection by differential data, to the microcontroller 16 throughanother serial link at 4800 bauds according to protocol ASCIINMEA-0183.For each request of position coming from the guidance resident programof the telephone 1, the microcontroller 16 transmits the position.

Preferably, the telephone will be of the smart phone type, with a largescreen incorporating the functionalities of an electronic organizer andpossessing a Java virtual machine. It is preferable for the navigationalaid program to be written in Java by Sun and be resident on thetelephone, making it possible to write a single program compatible withseveral telephones. Plant installation is also possible. Preferably,during at least one of the exchanges with the server 5, the telephone 1will give the version number of its navigational aid program to theserver 5 which will verify if it is really the last version. If not, theserver 5 will send a message to the telephone 1 informing it of theavailability of a new version. The telephone will display the messageand propose an update of its navigational aid program to the user. If heagrees, the server will then transmit the new program to the telephone1. This is mentioned as an example, the use of other types of telephonesand of operating systems and/or languages being possible, for exampletelephones with integrated electronic organizers of the WinCE fromMicrosoft type.

According to another preferred implementation mode, the mobile terminal1,2 is made of an electronic organizer of the 3COM Palm Pilot type andcomprises a GPS receiver and a GSM communications module. The GPSreception and GSM modules are integrated into the same block alsocomprising a microcontroller 16, a digital-to-analog converter 21 and aloudspeaker 23. The GPS and GSM module is removable and comprises a base9 making it possible to connect it to the electronic organizer. A lightpen is used for entering the data. The in-car guidance program is aresident program on the electronic organizer. This is mentioned as anexample, since other types of electronic organizers can be used, such asthe Psion.

According to another implementation mode which could be common to thepreceding modes, the mobile terminal 1,2 transmits its position and,eventually its speed, regularly to the server 5. The server stores thisinformation and can use it to update its data on road conditions, butalso for an eventual reply to a request from a terminal other than themobile terminal 1,2 from where the position comes. This makes itpossible to offer vehicle localization and follow-up services as well asfleet management services.

Although the invention has been described with the aid of the preferredimplementation modes, it will be clear for specialists and experts thatseveral modifications can be made in the shape and details withoutdeparting from the range, scope and spirit of this invention. Inparticular, the described system can also be used for the automaticguidance of a driverless vehicle, for the guidance of planes, ships orpedestrians; this system can also be used on other types of terminals,for instance a device pre-installed in the vehicle, integrated to thecar radio, to a board computer or to a chronotachograph; furthermore,the positioning receiver and all the processing units can be integratedinto the telephone device. Furthermore, the described server 5 can infact be made of several servers, these being distributed in order todivide the work according to geographic or calculations capabilityconstraints.

Also, all the data is not necessarily directly accessible to theseservers. Some of the data can be located on other servers, with thepossibility of a means of communications between them, through Internetfor instance.

What is claimed is:
 1. Interactive process for use as a real-timenavigational aid by which a mobile terminal (1,2), with means ofpositioning (18,19) transmits, through a wireless network, itineraryrequests to a fixed server (5) which transmits, in answer to the mobileterminal (1,2) and using the same network, itinerary data; characterizedby the fact that the itinerary data comprise the latitudes andlongitudes of at least one extremity of the straight line or arcsegments forming the itinerary; by the fact that the mobile terminal(1,2) develops real-time guidance messages according to the position ofthe mobile terminal (1,2) compared to the itineraries received by theserver (5); by the fact that, when answering the mobile terminal (1,2),the server (5) also transmits data concerning the roads intersectingwith the itinerary; by the fact that, when answering the mobile terminal(1,2) the server (5) also transmits data concerning a proximity areaaround the itinerary; by the fact that if the mobile terminal (1,2)deviates from the itinerary by taking one of the intersections, themobile terminal (1,2) obtains, without any additional connection to theserver (5), a new itinerary according to its position and the data ofthe proximity area and transmits guidance messages to this effect; andby the fact that if the mobile terminal (1,2) leaves the proximity area,the mobile terminal (1,2) automatically transmits a new itineraryrequest to the server (5), a request which also includes data concerningthe position of the mobile terminal (1,2).
 2. Process according to claim1, characterized by the fact that the server (5) saves in its memory theitinerary transmitted to the mobile terminal (1,2); by the fact that theserver (5) receives real-time information on the traffic conditions; bythe fact that the server (5) verifies if some of this informationconcern segments which are part of the itinerary or the proximity area;by the fact that, in the even of an incident affecting the itinerary,the server (5) estimates the possibility of a more advantageousitinerary; and by the fact that the server (5) connects with the mobileterminal (1,2) in order to transmit data on the incident and, ifnecessary, a new itinerary.
 3. Process according to claim 1,characterized by the fact that the itinerary data sent by the server (5)comprise displays of the places in the itinerary where a choice has tobe made, and by the fact that the displays are similar to the view aperson can have of these places when driving towards them whilefollowing the itinerary.
 4. Process according to claim 1 characterizedby the fact that the server (5) transmits data concerning generalinformation on the itinerary.
 5. Process according to claim 1,characterized by the fact that the guidance messages transmitted by themobile terminal (1,2) are made in sound form.
 6. Process according toclaim 5, characterized by the fact that at least one part of the soundmessages are developed by the server (5) which transmits them to themobile terminal (1,2) in digital audio form; by the fact that the mobileterminal (1,2) stores the sound messages, and by the fact that themobile terminal (1,2) transmits, at an appropriate time according to itsposition, the sound messages already stored, either as is or incombination.
 7. Process according to claim 1, characterized by the factthat the requests are formulated in voice form.
 8. Process according toclaim 7 characterized by the fact that the mobile terminal (1,2)digitizes the voice requests; by the fact that the mobile terminal (1,2)extracts analysis parameters from them; by the fact that the mobileterminal transmits its position and the analysis parameters to theserver (5); by the fact that the server (5) proceeds to an automaticrecognition of the voice requests based on the analysis parametersalready transmitted; by the fact that the server (5) determines thenature of the requests based on voice recognition and the position ofthe mobile terminal (1,2) and by the fact that the server (5) transmitsits answer to the mobile terminal (1,2).
 9. Process according to claim1, characterized by the fact that the means of positioning of the mobileterminal (1,2) comprise a satellites positioning receiver (18, 19); bythe fact that the server (5) obtains differential information forcorrecting the satellites positioning system from at least one fixedstation (6) covering the operating area of the mobile terminal (1,2); bythe fact that the server (5) transmits differential information to themobile terminal (1,2), and by the fact that transmission is executedthrough the same network used for the other data exchanges between themobile terminal (1,2) and the server (5).
 10. Process according to claim9 characterized by the fact that the server (5) uses SMS short messagesto transmit corrective differential information to the mobile terminal(1,2).
 11. Fixed server (5) for implementing claim 1, characterized bythe fact that the server (5) is an Internet server (5).
 12. Processaccording to claim 1, characterized by the fact that the mobile terminal(1,2) transmits its position to the server (5) on a regular basis; bythe fact that the positions are stored by the server (5); by the factthat at least one third party terminal contacts the server (5) totransmit requests concerning the mobile terminal (1,2) and by the factthat the server (5) answers by transferring cartographic datacorresponding to at least one of the positions of the mobile terminal(1,2).
 13. Process according to claim 1, characterized by the fact thatthe server (5) receives requests for the calculation of an itineraryfrom a third party terminal and by the fact that the server (5)transmits the itinerary requested by the third party to the mobileterminal (1,2).
 14. Process according to claim 1, characterized by thefact that the server (5) transmits to the mobile terminal (1,2), acomputer program through which it can execute navigational aidfunctions; by the fact that the mobile terminal (1,2) stores the programand by the fact that the mobile terminal (1,2) executes the program forperforming navigational aid functions.
 15. Mobile terminal (1,2) forimplementing claim 1, characterized by the fact that only one module (1)using a single radio communication network is used at a time fortransmitting requests, for receiving itineraries answers and forreceiving corrective differential information of satellites positioning.16. Mobile terminal (1,2) according to claim 15, characterized by thefact that the communications module is a portable radiotelephone (1); bythe fact that the radiotelephone is connected in a removable way to anaccessory (2) fixed inside a vehicle, and by the fact that the accessory(2) is connected to or integrates a satellites positioning receiver(19).
 17. Mobile terminal (1,2) according to claim 16, characterized bythe fact that the radiotelephone (1) is portable; by the fact that it isconnected to an accessory (2) fixed inside a vehicle; by the fact thatthe accessory (2) is connected or integrates a microphone(23), adigital-to-analog converter (21) and the means for extracting theanalysis parameters to be passed on to the telephone (1) fortransmission to the server (5) in view of a voice recognition operation.18. Mobile terminal (1,2) for implementing claim 1, characterized by thefact that it is formed of an electronic organizer, of a radiocommunications module and a satellites positioning receiver and by thefact that at least one of the communications module and the satellitespositioning receiver is a removable accessory.